add feature flag for fixed wind data mode and enable on VL3

[kaosfere]

Hi! I found this mod from someone on the Bush League Legends discord. They were concerned about whether it would conflict with the Working Title G3X Touch I'm developing for them. At first I didn't think an engine mod would, but then I noticed you were also altering avionics, including CommonPFD_MFD.js.

The way this mod is written it will break the wind data bug of every plane that uses the stock CommonPFD_MFD.js -- which means everything using the stock G1000 in addition to whatever use is modified to use it. (It turns out it wouldn't break the Working Title mods because we put stuff into our own directories for just that reason, but not everyone uses the WT G1000).

This PR creates a feature flag that can be set in a plane's panel.xml to force a given wind data mode, and then adds it to your modded VL3. This will allow you to have the feature that you want without breaking wind data for everything else. This is the way that Asobo themselves turn various things such as synthetic vision on and off within a glass display. I also threw in some of the logic we have in the Working Title avionics to correct the way wind data is displayed when you're on the ground for free. :D

As a side note: do you really want this particular plane to be forced to mode 1? Or was that just meant to get something to show up quickly? If it's the latter, you might want to think about pulling the avionics out of this entirely and suggesting that people try the Working Title G3X package. It adds the wind data bug, too, but it also creates a configuration menu item for it so people can select their mode. With a small modification I'm going to make soon it will also take advantage of the Working Title preference persistence system to peoples favorite mode stays set between sessions.

(The WT G3X also does a little bit of restyling to closer match the real thing, puts the CAS alert system where it should be, and includes support for an optional auto-regulated pitot heater. I'm not sure if the VL3 has this in real life, but it's configurable via a feature flag just like I've set up here for your wind data. Very soon there will be NEXRAD support, too.)

The G3X is currently in alpha mode, meaning it isn't anywhere close to feature complete, but it's already being used by the BLL guys who appreciate the enhancements.

Either way, even if you're not interested in having folks use that and want to keep your own avionics, this patch will give you a politer way of doing it. :)

I hope this helps!

If you want to try out the WT G3X for yourself the code is here, but since it uses our build system that directory won't be complete on its own. You might find it easier to just grab a compiled package. Here's the latest alpha build:

workingtitle-gx-alpha3.zip

(This is also fully compatible with the Working Title G1000 if you use that.)